The invention relates to photocatalytic materials. More particularly, the invention relates to photocatalytic materials comprising nanocrystalline quantum dots chemically coupled to molecular catalysts. Even more particularly, the invention relates to photoelectrolytic devices comprising such photocatalytic materials.
The broad field of photocatalysis utilizes numerous molecular catalyst or semiconductor nanocrystalline catalysts. However, limited attempts have been made to couple molecular and serniconductor components in a functional assembly.
In one approach, the light activated component is the molecular catalyst rather than the semiconductor. The semiconductor is a “passive” component of the assembly, as activation requires absorption of a photon by the molecular catalyst and subsequent electron transfer into the semiconductor. Moreover, this approach utilizes mesoscopic nanocrystalline materials with average particle sizes of at least about 20 nm rather than quantum size (i.e., 2-10 nm diameter) materials, thus eliminating the possibility of taking advantage of quantum size effects.
Current photocatalytic materials rely on mesoscopic semiconducting materials that are unable to capitalize on quantum effects. In addition, the dyes that are used to sensitize the photocatalytic material have poor stability, low absorptivity, and narrow absorptivity ranges, and a limited ability to convert photon energy to charges. Therefore, what is needed is a photocatalytic material having improved stability. What is also needed is a photocatalytic material having a broader absorptivity range and improved capability to convert photon energy to electronic charge.